Comparing bright-target surface spectral-reflectance estimates obtained from IRS P6 LISS III to those obtained from Landsat 5 TM and Landsat 7 ETM+

Abstract

Since 2008 there have been a limited number of Landsat 5 thematic mapper (TM) images acquired between April and October in Australia. Consequently, TM imagery may not be available at the desired time of year for some monitoring applications. IRS (Indian Remote Sensing) P6 LISS (Linear Imaging and Self Scanner) III imagery has been acquired over Australia since 2008 and represents an alternative, Landsat-like, data source to fill the Landsat 5 TM temporal gap. To be useful for the continuation of long-term monitoring, the LISS III imagery needs to provide similar surface-reflectance estimates to Landsat 5 TM. A time series of spatially averaged sensor-radiance estimates for 2008 was derived from Landsat 5 TM, Landsat 7 enhanced thematic mapper plus (ETM+) and IRS P6 LISS III imagery for two highly reflective, spectrally invariant, claypans in Queensland, Australia. The radiance values were converted to surface reflectance using the atmospheric transfer modelling code 6S. Adjustment factors, to account for the spectral band difference effects between sensors, were computed from field-measured reflectance spectra. The LISS III surface-reflectance estimates were found to be consistently lower than the Landsat estimates. The difference between the IRS P6 LISS III reflectances and the median Landsat 5 TM reflectances were approximately 20%, 22%, 12% and 3.5% for Landsat bands 2, 3, 4 and 5, respectively. Further research is required to determine whether updated calibration parameters for the LISS III sensor are required.

Acknowledgements

Geoscience Australia donated three of the IRS images used in this study. We greatly appreciate the free Landsat made available by the USGS.